<!DOCTYPE html>
<html>
<head>
  <script src="https://cdn.rawgit.com/konvajs/konva/1.4.0/konva.min.js"></script>
  <meta charset="utf-8">
  <title>Konva Blur Image Demo</title>
  <style>
    body {
      margin: 0;
      padding: 0;
      overflow: hidden;
      background-color: #F0F0F0;
    }
    #slider {
      position: absolute;
      top: 20px;
      left: 20px; 
    }
  </style>
</head>
<body>
  <div id="container"></div>
  <input id="slider" type="range" min="0" max="40" step="0.05" value="20">
  <script>
    function loadImages(sources, callback) {
      var images = {};
      var loadedImages = 0;
      var numImages = 0;
      for(var src in sources) {
        numImages++;
      }
      for(var src in sources) {
        images[src] = new Image();
        images[src].onload = function() {
          if(++loadedImages >= numImages) {
            callback(images);
          }
        };
        images[src].src = sources[src];
      }
    }
    function buildStage(images) {
      var stage = new Konva.Stage({
        container: 'container',
        width: 300,
        height: 200
      });

      var layer = new Konva.Layer();

      var lion = new Konva.Image({
        image: images.lion,
        x: 80,
        y: 30,
        blurRadius: 20,
        draggable: true
      });

      lion.cache();
      lion.filters([Konva.Filters.Blur]);
      layer.add(lion);
      stage.add(layer);
      var slider = document.getElementById('slider'); 
      slider.onchange = function() {
        lion.blurRadius(slider.value);
        layer.batchDraw();    
      };
    }

    var sources = {
      lion: '/assets/lion.png'
    };

    loadImages(sources, buildStage);
  </script>

</body>
</html>